Interactive Guide Grade 3

How to Dress a Duck

15

(Chapter Two)

Experiment! H ave you ever heard the expression, “like water off a duck’s back”? You can see for yourself what it means in this experiment. You can also see how oil makes a duck’s feathers waterproof. Cut one side out of a paper grocery sack. Working over the kitchen sink, pour one teaspoon of vegetable oil onto the center of the cut-out piece. Smooth the oil into a circle, about the size of your hand, until it is all absorbed by the paper. Put the paper in the bottom of the sink. Now run a trickle of cold water over the paper. Does the water behave differ ently when it flows over the oiled part of the paper than when it flows over the un-oiled part? Now tilt the paper a little. The water will make little “beads” on the oily part. Can you see that the water doesn’t “stick” to the oiled part of the paper, but runs “like water off a duck’s back”? Because oil sheds water, it is also often used to protect machines from damage caused by water. Ask a parent to show you some of the machines around your home that are oiled for protection.

2. What does the duck do to spread oil on its feathers?

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3. Describe webbed feet.

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6 How to Dress a Duck and Other Stories from Science

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